Boundary Waters Canoe Area Wilderness, Minnesota (© s.tomas/Shutterstock)

The Wilderness Act of 1964, passed 61 years ago today, established the legal definition of wilderness in the United States. Its purpose was to preserve areas 'where the earth and its community of life are untrammeled by man.' This landmark legislation created the National Wilderness Preservation System, protecting millions of acres from development, roads, and mechanized use.